EFADV_QUERY_MR(3)

💅 EFADV_QUERY_MR(3) — like, the EFA Direct Verbs manual, bestie 🦋

okay so this is page EFADV_QUERY_MR(3) from the EFA Direct Verbs Manual, and it's genuinely so good — it's all about peeking at the device-specific tea on a Memory Region. no cap, let's get into it ✨

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🌸 NAME 🌸

efadv_query_mr — query EFA specific Memory Region attributes 🎀

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✨ SYNOPSIS ✨

#include <infiniband/efadv.h>

int efadv_query_mr(struct ibv_mr *ibvmr, struct efadv_mr_attr *attr, uint32_t inlen);

like, that's the whole vibe. three args, one int back. slay 💅

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💖 DESCRIPTION 💖

so efadv_query_mr() queries device-specific Memory Region attributes. it's giving "let me find out what this MR is actually doing on the hardware" 🔥

compatibility is handled using the comp_mask and inlen fields — that's the whole mechanism, fr fr.

struct efadv_mr_attr {
    uint64_t comp_mask;
    uint16_t ic_id_validity;
    uint16_t recv_ic_id;
    uint16_t rdma_read_ic_id;
    uint16_t rdma_recv_ic_id;
};

now let's break down every field, one by one, because we do not skip ✨

• inlen — In (input! you set it): the size of struct efadv_mr_attr.
• comp_mask — the compatibility mask. iconic, necessary, does exactly what it says.
• ic_id_validity — the validity mask for the interconnect id fields. it tells you which of the id fields below actually have valid values in them:
  • EFADV_MR_ATTR_VALIDITY_RECV_IC_ID — means recv_ic_id has a valid value ✔️
  • EFADV_MR_ATTR_VALIDITY_RDMA_READ_IC_ID — means rdma_read_ic_id has a valid value ✔️
  • EFADV_MR_ATTR_VALIDITY_RDMA_RECV_IC_ID — means rdma_recv_ic_id has a valid value ✔️
• recv_ic_id — the physical interconnect the device uses to reach the MR for receive operation 🫶
• rdma_read_ic_id — the physical interconnect the device uses to reach the MR for RDMA read operation 💜
• rdma_recv_ic_id — the physical interconnect the device uses to reach the MR for RDMA write receive 🌈

three different interconnects, three different operations, all queried in one go — main character energy honestly 👑

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🎀 RETURN VALUE 🎀

efadv_query_mr() returns 0 on success, or the value of errno on failure (which indicates the failure reason). so like, zero is the good ending, anything else means go read errno and find out what went wrong 😭

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🦋 SEE ALSO 🦋

• efadv(7) — the big one, go read it next, iykyk 💫

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⭐ NOTES ⭐

• compatibility mask (comp_mask) is an out field and currently has no values. so it's out-only for now and there's literally nothing in it — not me telling you to check it, because there's nothing to check 🙈

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🌸 AUTHORS 🌸

Michael Margolin <mrgolin@amazon.com> — thank you for your service, king 👑💖

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and that's the whole page bestie, you ate that 🫶 this was efa, dated 2023-11-13, and it's the EFADV_QUERY_MR(3) page — go forth and query those MRs, periodt 💅✨